Information processing apparatus, non-transitory computer-readable storage medium storing information processing program, information processing system, and information processing method

ABSTRACT

An example information processing apparatus disposes a flat ground representing a terrain, and an object on the ground, in a virtual space, and performs coordinate conversion on each of vertices of the flat ground and the object on the ground, based on a deformation parameter, so as to change the entire terrain into a drum shape. Thereafter, the information processing apparatus renders an image of the virtual space including the terrain deformed into the drum shape.

CROSS REFERENCE TO RELATED APPLICATIONS

The disclosures of Japanese Patent Application Nos. 2018-212370 and2018-212371, both filed Nov. 12, 2018, are incorporated herein byreference.

FIELD

The present disclosure relates to information processing apparatuses,information processing programs, information processing systems, andinformation processing methods that are capable of generating an image.

BACKGROUND AND SUMMARY

As a related art, for example, there is a game apparatus that performscoordinate conversion on a flat surface position coordinate system forrepresenting the position of a player object on a flat game field into acoordinate system based on a curved game field, and disposes a playerobject on the curved game field based on curved surface positioncoordinates obtained by the coordinate conversion, and displays theplayer object.

However, in the above related art, it is necessary to previously preparethe curved game field. Therefore, concerning a terrain provided in avirtual space, there is room for improvement of development efficiency.

Therefore, it is an object of this embodiment to provide an informationprocessing apparatus, information processing program, informationprocessing system, and information processing method that can improvedevelopment efficiency for a terrain provided in a virtual space.

To achieve the above, this non-limiting example embodiment has thefollowing features.

An information processing apparatus according to this embodimentexecutes disposing a terrain object representing a terrain in a virtualspace, disposing a second object on the terrain object, setting adeformation parameter indicating a degree of deformation of the terrain,performing coordinate conversion on vertex coordinates included in theterrain object and the second object so as to deform the entire terrainto the degree corresponding to the deformation parameter, and renderingthe terrain object and the second object after the coordinate conversionis performed, based on a virtual camera.

Thus, the coordinate conversion is performed on the vertex coordinatesof the terrain object disposed in the virtual space and the secondobject on the terrain object so as to deform the entire terrain. As aresult, the entire terrain can be deformed instead of previouslypreparing all terrain objects and other objects that are alreadydeformed. Therefore, development efficiency can be improved.

In another feature, the information processing apparatus may include agraphics processor having a vertex shader function. The graphicsprocessor may perform the coordinate conversion using the vertex shaderfunction.

Thus, the coordinate conversion is performed by the graphics processorusing the vertex shader function. Therefore, the coordinate conversioncan be performed at high speed.

In another feature, the deformation parameter may be related to acurvature. The terrain object may include a flat reference surface. Thecoordinate conversion may be performed on the vertex coordinate so as tochange the flat reference surface to a curved surface shape depending onthe deformation parameter.

Thus, the flat terrain can be deformed into a curved surface shape.Therefore, a curved terrain can be obtained from a previously preparedflat terrain. It is not necessary to previously prepare a curvedterrain.

In another feature, the information processing apparatus may furtherexecute controlling the virtual camera. The deformation parameter may beset, depending on a state of the virtual camera.

Thus, for example, the flat reference surface can be deformed into acurved surface shape, depending on the state of the virtual camera.

In another feature, a line-of-sight direction in the virtual space ofthe virtual camera may be allowed to be set to a first direction or asecond direction pointing further downward than the first direction. Thedeformation parameter may be set so that the curvature is a firstcurvature when the line-of-sight direction of the virtual camera is thefirst direction, and the curvature is a second curvature greater thanthe first curvature when the line-of-sight direction of the virtualcamera is the second direction.

Thus, the curvature can be decreased when the line-of-sight direction ofthe virtual camera is the first direction, and the curvature can beincreased when the line-of-sight direction of the virtual camera is thesecond direction. For example, when the line-of-sight direction of thevirtual camera is the first direction (e.g., a lateral direction), thecurvature is relatively decreased, and therefore, it is possible toprevent the user from having an unnatural feeling.

In another feature, the line-of-sight direction in the virtual space ofthe virtual camera may be allowed to be set to a third directionpointing further downward than the second direction. The deformationparameter may be set so that the curvature is a third curvature smallerthan the first and second curvatures when the line-of-sight direction ofthe virtual camera is the third direction.

Thus, when the line-of-sight direction of the virtual camera is set tothe third direction pointing further downward than the second direction,the curvature can be relatively decreased. For example, when the terrainin the virtual space is viewed from above, the curvature can bedecreased, and therefore, a flat or nearly flat terrain can bedisplayed.

In another feature, the virtual camera may be allowed to be set to viewthe terrain object in the virtual space from directly above. When thevirtual camera is set to view the terrain object in the virtual spacefrom directly above, the coordinate conversion may not be performed.

Thus, when the virtual camera is set to view the terrain object in thevirtual space from directly above, the coordinate conversion is notperformed. A flat terrain can be displayed like a map.

In another feature, the deformation parameter related to the curvaturemay indicate an angle. The coordinate conversion may be performed oneach vertex coordinate, depending on a position of the vertex coordinatein a depth direction along the flat reference surface, so as to convertthe flat reference surface into a surface forming a portion of the sidesurface of a cylinder, where a line extending in the depth directionalong the flat reference surface forms an arc having a central angleequal to the angle indicated by the deformation parameter.

Thus, the coordinate conversion is performed on each vertex coordinate,depending on the position of the vertex coordinate in the depthdirection along the flat reference surface. Therefore, the flatreference surface can be deformed into the side surface of a cylinder.

In another feature, the coordinate conversion may be performed on eachvertex coordinate after a value is added to a coordinate valueindicating a position of the vertex coordinate in the depth directionalong the flat reference surface.

Thus, the coordinate conversion is performed after a value is added to acoordinate value indicating a position in the depth direction along thereference surface. In this case, the vertex coordinate after thecoordinate conversion is further moved on an arc in a circumferentialdirection than when the coordinate conversion is performed withoutadding the value. As a result, the entire cylindrical terrain can bemoved in the circumferential direction. For example, in the case wherethe virtual camera is fixed to the virtual space, apparent movement ofthe virtual camera can be achieved by turning the cylindrical terrain.

In another embodiment, an information processing program that causes acomputer of an information processing apparatus to execute the aboveprocesses may be provided. In still another embodiment, an informationprocessing system for executing the above processes may be provided, andan information processing method to be executed in the informationprocessing system may be provided.

According to this embodiment, an entire terrain can be deformed bycoordinate conversion instead of previously preparing all terrainobjects that are already deformed. Therefore, development efficiency canbe improved.

These and other objects, features, aspects and advantages of the presentexemplary embodiment will become more apparent from the followingdetailed description of the present exemplary embodiment when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a non-limiting example game system 1 in this embodiment,

FIG. 2 is a block diagram showing a non-limiting example internalconfiguration of the game system 1,

FIG. 3 is a diagram showing a non-limiting example virtual space inwhich a game of this embodiment is played,

FIG. 4A is a diagram showing a non-limiting example terrain part GP1that forms a part of a cliff object or ground object,

FIG. 4B is a diagram showing a non-limiting example terrain part GP2that forms a part of a cliff object,

FIG. 4C is a diagram showing a non-limiting example terrain part GP3that forms a part of a cliff object,

FIG. 5 is a diagram showing a non-limiting example terrain formed bydisposing a plurality of kinds of terrain parts in the virtual space,

FIG. 6 is a diagram showing a non-limiting example terrain obtained bydeforming each terrain part of the terrain of FIG. 5 that is formed bydisposing a plurality of terrain parts,

FIG. 7 is a diagram showing a non-limiting example image displayed on adisplay 12 in the case where a first deformation process is notperformed on any terrain part,

FIG. 8 is a diagram showing a non-limiting example image displayed onthe display 12 in the case where the first deformation process isperformed on each terrain part,

FIG. 9 is a diagram showing a non-limiting example image that isdisplayed on the display 12 when a user character 50 performs an actionto scrape a portion of a cliff object,

FIG. 10A is a diagram showing the virtual space as viewed from abovebefore the user character 50 performs an action to scrape a portion of acliff object,

FIG. 10B is a diagram showing the virtual space as viewed from aboveafter the user character 50 performs an action to scrape a portion of acliff object,

FIG. 11 is a diagram showing a non-limiting example image that isdisplayed on the display 12 when the user character 50 performs anaction to dig the ground and heap earth on the ground,

FIG. 12A is a diagram showing a non-limiting example virtual space asviewed from above before a terrain part GP1 is added,

FIG. 12B is a diagram showing a non-limiting example virtual space asviewed from above after a terrain part GP1 is added.

FIG. 13 is a diagram showing a non-limiting example virtual space afterthe first deformation process is performed and before a seconddeformation process is performed,

FIG. 14 is a diagram showing a non-limiting example virtual space afterthe second deformation process is performed,

FIG. 15 is a diagram showing a non-limiting example virtual space asviewed in a direction parallel to an x-axis before the seconddeformation process is performed,

FIG. 16 is a diagram showing a non-limiting example virtual space asviewed in a direction parallel to the x-axis after the seconddeformation process is performed,

FIG. 17A is a diagram showing a non-limiting example image that isdisplayed on the display 12 when the line-of-sight direction of avirtual camera VC is a first direction and the second deformationprocess is not performed,

FIG. 17B is a diagram showing a non-limiting example image that isdisplayed on the display 12 when the line-of-sight direction of thevirtual camera VC is the first direction and the second deformationprocess is performed,

FIG. 18A is a diagram showing a non-limiting example image that isdisplayed on the display 12 when the line-of-sight direction of thevirtual camera VC is a second direction and the second deformationprocess is not performed,

FIG. 18B is a diagram showing a non-limiting example image that isdisplayed on the display 12 when the line-of-sight direction of thevirtual camera VC is the second direction and the second deformationprocess is performed,

FIG. 19A is a diagram showing a non-limiting example image that isdisplayed on the display 12 when the line-of-sight direction of thevirtual camera VC is a third direction and the second deformationprocess is not performed,

FIG. 19B is a diagram showing a non-limiting example image that isdisplayed on the display 12 when the line-of-sight direction of thevirtual camera VC is the third direction and the second deformationprocess is performed,

FIG. 20 is a diagram showing the virtual space as viewed in a directionparallel to the x-axis before and after deformation by adding an offsetvalue to a z-coordinate value,

FIG. 21 is a diagram showing non-limiting example data stored in a bodyapparatus 2 (a DRAM 26 thereof), and

FIG. 22 is a flowchart showing a non-limiting example game processperformed in a processor 20 of the body apparatus 2.

DETAILED DESCRIPTION OF NON-LIMITING EXAMPLE EMBODIMENTS

(System Configuration)

A game system 1 (non-limiting example information processing system)according to this embodiment will now be described with reference to theaccompanying drawings. FIG. 1 is a diagram showing a non-limitingexample of the game system 1 of this embodiment. As shown in FIG. 1, thegame system 1 includes a body apparatus 2 as a game apparatus, a leftcontroller 3, and a right controller 4. The body apparatus 2 includes adisplay 12. Note that the left controller 3 and the right controller 4may be removable from the body apparatus 2.

The left controller 3 is controlled using the user's left hand, and theright controller 4 is controlled using the user's right hand. The leftcontroller 3 and the right controller 4 include a plurality of operationbuttons, and an analog stick as a direction input unit.

FIG. 2 is a block diagram showing a non-limiting example internalconfiguration of the game system 1. As shown in FIG. 2, the bodyapparatus 2 includes a processor 20, a slot interface 23, a slot 24, aflash memory 25, and a DRAM 26. The processor 20 includes a centralprocessing unit (CPU) 21 and a graphics processing unit (GPU) 22. TheCPU 21 can execute a game program to process operation data from thecontrollers 3 and 4, execute a game process based on the operation data,and transmit an instruction to the GPU 22 to generate an image. The GPU22 is a processor for performing image processing. The GPU 22 has avertex shader function for converting coordinates of vertices of avirtual object. Note that the CPU 21 and the GPU 22 may be mounted onseparate chips or may be mounted on a single chip as a system-on-a-chip(SoC).

The processor 20 is coupled to the slot interface 23, the flash memory25, the DRAM 26, and the display 12. The processor 20 is also coupledthrough a left interface to the left controller 3, and through a rightinterface to the right controller 4. An external storage medium isremovably inserted into the slot 24. The external storage medium storesa program (a game program described below) and data (part shape data andterrain part arrangement data, etc., described below). Note that theprogram and data may be previously stored in the flash memory 25, or maybe downloaded and stored into the flash memory 25 through a network(e.g., the Internet).

The program and data stored in the external storage medium (or the flashmemory 25) are loaded to the DRAM 26 during the start of a gamedescribed below. The CPU 21 executes the program to perform a gameprocess described below. The CPU 21 also transmits an instruction to theGPU 22 to display an image on the display 12, and the GPU 22 renders animage according to the instruction, and causes the display 12 to displaythe image. Note that the body apparatus 2 may be coupled to an externaldisplay apparatus different from the display 12, and an image generatedby the GPU 22 may be displayed on the external display apparatus.

(Overview of Game and Image Processing of This Embodiment)

Next, a game of this embodiment will be outlined. FIG. 3 is a diagramshowing a non-limiting example virtual space in which the game of thisembodiment is played. When the game program of this embodiment isexecuted, a virtual space is defined in the body apparatus 2, andvarious virtual objects are disposed in the virtual space. A user(player) moves a user character 50 in the virtual space using the leftcontroller 3 and the right controller 4, so that the game proceeds.

As shown in FIG. 3, an xyz orthogonal coordinate system is set in thevirtual space. The x-axis is a lateral direction axis of the virtualspace, the z-axis is a depth direction axis of the virtual space, andthe y-axis is a height direction axis of the virtual space. In thevirtual space, as virtual objects, a ground object 34, and a riverobject 33 that flows through the ground object 34, are disposed. Theground object 34 is a flat reference surface, e.g. a plane parallel tothe xz plane. Note that the ground object 34 may be a substantially flatplane that has irregularities or unevenness (a generally flat plane), ormay be an exactly flat plane that does not have irregularities orunevenness. In the virtual space, as virtual objects, cliff objects30-32 are also disposed. The ground object 34, the cliff objects 30-32,and the river object 33 are terrain objects representing the terrain inthe virtual space.

In addition, as virtual objects, a house object 40, a tree object 41,and the user character 50 are disposed on the terrain objects. The userplays the game by operating the user character 50. For example, the usercharacter 50 can move on the ground object 34, climb a cliff object, diga ditch on the ground object 34, scrape a cliff object, and add a newcliff object on the ground object 34 or a cliff object.

The terrain objects (the ground object 34, the river object 33, and thecliff objects 30-32) are formed of a plurality of kinds of terrainparts. In this embodiment, a plurality of kinds of terrain parts arepreviously prepared, and the ground object 34, the river object 33, andcliff objects are formed by disposing a plurality of kinds of terrainparts in the virtual space.

(Non-Limiting Example Terrain Parts)

Here, non-limiting example terrain parts will be described. FIG. 4A is adiagram showing a non-limiting example terrain part GP1 that forms apart of a cliff object or ground object. FIG. 4B is a diagram showing anon-limiting example terrain part GP2 that forms a part of a cliffobject. FIG. 4C is a diagram showing a non-limiting example terrain partGP3 that forms a part of a cliff object.

As shown in FIG. 4A, the terrain part GP1 includes a plurality ofvertices V. The plurality of vertices form the top surface S1, sidesurfaces S2, and bottom surface of the terrain part GP1. The top surfaceS1, the side surfaces S2, and the bottom surface form the terrain partGP1. For example, the top surface S1 and bottom surface of the terrainpart GP1 are in the shape of a square with a length of, for example, 1 min the lateral direction (x-axis direction) and depth direction (thez-axis direction) of the virtual space. The side surfaces S2 of theterrain part GP1 are in the shape of a rectangle. Thus, the terrain partGP1 is in the shape of a rectangular parallelepiped with a length of 1 min the lateral direction (x-axis direction) and depth direction (thez-axis direction) of the virtual space. Part shape data that indicatesthe shape of the terrain part GP1 is previously stored in the externalstorage medium. The part shape data indicating the shape of the terrainpart GP1 contains data indicating relative positions (e.g., positionsrelative to a representative vertex) of the vertices V of the terrainpart GP1. When the terrain part GP1 is disposed in the virtual space,the coordinate values in the virtual space of each vertex are determinedbased on the position thereof relative to the representative vertex.

As shown in FIG. 4B, the terrain part GP2 includes a plurality ofvertices V. The plurality of vertices V form the top surface S1, sidesurfaces S2, and bottom surface S3 of the terrain part GP2. The terrainpart GP2 forms a part of a cliff object. The terrain part GP2 has ashape different from that of the terrain part GP1. For example, the topsurface S1 of the terrain part GP2 is in the shape of an isosceles righttriangle with a length of 1 m in the horizontal and depth directions ofthe virtual space. The top surface S1 and the three side surfaces S2form a triangular prism. The bottom surface S3 is in the shape of asquare with a length of 1 m in the horizontal and depth directions ofthe virtual space, and a half of the bottom surface S3 forms the bottomsurface of the triangular prism. Part shape data indicating the shape ofthe terrain part GP2 is previously stored in the external storagemedium. The part shape data indicating the shape of the terrain part GP2contains data indicating the relative position of each vertex V of theterrain part GP2.

As shown in FIG. 4C, the terrain part GP3 includes a plurality ofvertices V. The plurality of vertices V form the L-shaped top surfaceS1, side surfaces S2, and bottom surface S3 of the terrain part GP3. Theterrain part GP3 forms a part of a cliff object. The terrain part GP3has a shape different from those of the terrain parts GP1 and GP2. Forexample, the terrain part GP3 has a shape obtained by cutting away aportion of a rectangular parallelepiped with a length of 1 m in thelateral direction (x-axis direction) and depth direction (the z-axisdirection) of the virtual space. The bottom surface S3 of the terrainpart GP3 is in the shape of a square with a length of 1 m in thehorizontal and depth directions. Part shape data indicating the shape ofthe terrain part GP3 is previously stored in the external storagemedium. The part shape data indicating the shape of the terrain part GP3contains data indicating the relative position of each vertex V of theterrain part GP3.

As shown in FIGS. 4A-4C, each terrain part is in the shape of a squarein the lateral direction (x-axis direction) and depth direction (thez-axis direction) of the virtual space. In other words, each terrainpart has a square shape as viewed from directly above (in the y-axisdirection).

Although FIGS. 4A-4C show the surfaces (e.g., the top surface and sidesurfaces) of each terrain part as a flat surface, the surfaces of eachterrain part may be an irregular or uneven surface.

In addition to the terrain parts shown in FIGS. 4A-4C, various otherterrain parts are previously prepared. For example, a terrain part thatforms a part of the river object 33, a terrain part that forms a part ofa boundary portion between a river and the ground, a terrain part thatforms a part of a sandy road, etc., are prepared. Part shape dataindicating these kinds of terrain parts is previously stored in anexternal storage medium.

(Construction of Terrain Using Terrain Parts)

By disposing the above kinds of terrain parts in the virtual space, aterrain is formed in the virtual space. FIG. 5 is a diagram showing anon-limiting example terrain formed by disposing a plurality of kinds ofterrain parts in the virtual space.

FIG. 5 shows the entire terrain in the virtual space as viewed above. Asshown in FIG. 5, when the terrain in the virtual space is viewed fromabove, the terrain looks like a flat plane in which a plurality ofsquares are disposed in a grid pattern. Each square is the top surfaceor bottom surface of a terrain part. For example, the cliff object 30 isformed by disposing eight terrain parts GP1. In this case, each terrainpart GP1 is previously configured so as to allow the vertices V in anadjoining portion of adjoining terrain parts GP1 to share the samepositions. In other words, when a first terrain part GP1 adjoins asecond terrain part GP1, a vertex V of the first terrain part GP1 and avertex V of the second terrain part GP1 in an adjoining portion arelocated at the same position.

The cliff object 31 is formed of seven terrain parts GP1 and one terrainpart GP2. The cliff object 32 is formed of three terrain parts GP1 andone terrain part GP3. Also in this case, each terrain part is previouslyconfigured so as to allow the vertices V in an adjoining portion ofadjoining terrain parts to share the same positions.

The ground object 34 is formed by disposing a plurality of terrain partsGP1 in a grid pattern extending in the horizontal and depth directions.The river object 33 is formed by disposing a plurality of terrain partsGP4 and one terrain part GP5. The terrain part GP4 is previouslyprepared for forming a river. The terrain part GP5 includes a boundaryportion between a river and the ground. Also in this case, each terrainpart is previously configured so as to allow the vertices V in anadjoining portion of adjoining terrain parts to share the samepositions. For example, terrain parts are previously configured so that,in the rightmost column of FIG. 5, the vertices V of the second terrainpart GP4 from the bottom and the vertices V of the third terrain partGP1 from the bottom in the adjoining portion are located at the samepositions.

In this embodiment, terrain part arrangement data indicating anarrangement of a plurality of kinds of terrain parts is previouslystored in an external storage medium. By disposing a plurality ofterrain parts based on the terrain part arrangement data, a terrain isformed in the virtual space.

Note that the above terrain parts include terrain parts that are allowedto adjoin each other and terrain parts that are not allowed to adjoineach other. For example, a terrain part that forms a part of a “sandyroad” and a terrain part that forms a part of a “river” are not allowedto adjoin each other. Specifically, for two terrain parts that areallowed to adjoin each other, the positions of the vertices thereof arepreviously set so that when the two terrain parts adjoin each other, thevertices thereof in the adjoining portion share the same positions.

In the terrain part arrangement data, the arrangement of terrain partsis determined so that terrain parts that are not allowed to adjoin eachother are not located adjacent to each other. In addition, as describedbelow, when a new terrain part is added to the virtual space or when aterrain part disposed in the virtual space is replaced with anotherterrain part, control is performed in such a manner that terrain partsthat are not allowed to adjoin each other are not located adjacent toeach other.

(First Deformation Process)

Here, when a terrain is formed by disposing a plurality of previouslystored terrain parts based on the terrain part arrangement data, theresultant terrain in the virtual space may be monotonous and unnatural.Therefore, in this embodiment, performed is a first deformation processof deforming (applying a strain to) each terrain part for a terrainformed by disposing a plurality of terrain parts based on the terrainpart arrangement data. In this embodiment, the first deformation processis performed each time an image is rendered. By performing the firstdeformation process, a terrain formed by disposing a plurality ofterrain parts is deformed, so that the resultant terrain looks natural.

FIG. 6 is a diagram showing a non-limiting example terrain obtained bydeforming each terrain part of the terrain of FIG. 5 that is formed bydisposing a plurality of terrain parts. As shown in FIG. 6, by deforminga plurality of terrain parts disposed based on the terrain partarrangement data, each terrain part has a curved shape (wavy shape)instead of a linear shape.

Specifically, in the first deformation process, each terrain partdisposed in the virtual space based on the terrain part arrangement datais deformed by displacing the vertices of the terrain part, depending onthe positions in the virtual space of the vertices. More specifically,each vertex of a terrain part disposed in the virtual space is displacedin the lateral direction (x-axis direction) and depth direction (thez-axis direction) of the virtual space.

A lower portion of FIG. 6 shows a vertex V (x, z) of terrain parts GP1and GP4 before deformation and a vertex V′ (x+dx, z+dz) of the terrainparts GP1 and GP4 after deformation. Here, the displacement amount dx ofthe x-coordinate value of the vertex V and the displacement amount dz ofthe z-coordinate value of the vertex V are calculated based on afunction having a predetermined waveform. For example, the displacementamounts dx and dz are calculated by the following expressions.

dx=cos(z)×cos(z)×cos(nz)×cos(mz)×α  (1)

dz=cos(x)×cos(x)×cos(nx)×cos(mx)×α  (2)

In expression 1, “z” is the z-coordinate value of the vertex V in thevirtual space before deformation. In expression 2, “x” is thex-coordinate value of the vertex V in the virtual space beforedeformation. In addition, “n” and “m” are a positive integer, e.g. maybe n=3 and m=5. In addition, α is a previously determined coefficient.

By adding, to all vertices of each terrain part, respective displacementamounts calculated by expressions 1 and 2, the vertex V (x, y, z) isdisplaced to V′ (x+dx, y, z+dz). As a result, each terrain part isdisplaced in the x-axis and z-axis directions. Note that they-coordinate value of each vertex V remains unchanged irrespective ofdeformation.

The calculation by expressions 1 and 2 is performed by the vertex shaderfunction of the GPU 22. The GPU 22 changes, according to an instructionfrom the CPU 21, the position in the virtual space of each vertexlocated based on the terrain part arrangement data, using expressions 1and 2. As a result, each terrain part is deformed, so that the entireterrain in the virtual space is deformed. Thereafter, the GPU 22performs a rendering process so that an image is displayed on thedisplay 12 as shown in FIG. 6. Specifically, each time an image isdisplayed on the display 12 (for each frame), the GPU 22 displaces thevertices of each terrain part using the vertex shader function togenerate an image in which a terrain formed based on the plurality ofpieces of part shape data and the terrain part arrangement data isdeformed.

As can be seen from expressions 1 and 2, in this embodiment, a functionhaving a predetermined waveform is defined by a combination of aplurality of trigonometric functions having different periods. As aresult, different displacement amounts can be added to differentvertices, depending on the position of the vertex V in the virtualspace. Even the same kind of terrain parts can be deformed intodifferent shapes if the terrain parts are located at differentpositions. In addition, the displacement amounts dx and dz aredetermined by a combination of trigonometric functions having differentperiods, and therefore, it is difficult for the user to be aware of theperiods. Therefore, a terrain that looks natural to the user can becreated.

Note that expressions 1 and 2 are merely for illustrative purposes, andthe displacement amounts dx and dz for a vertex V may be calculatedaccording to other expressions. Alternatively, the displacement amountsdx and dz for a vertex V may be randomly determined, depending on theposition in the virtual space of the vertex V.

FIG. 7 is a diagram showing a non-limiting example image displayed onthe display 12 in the case where the first deformation process is notperformed on any terrain part. FIG. 8 is a diagram showing anon-limiting example image displayed on the display 12 in the case wherethe first deformation process is performed on each terrain part.

As shown in FIG. 7, in the case where the first deformation process isnot performed, the cliff object 31 disposed in the virtual space hasgenerally linear and angular shapes. A boundary between the ground 34and the river object 33 also has linear and angular shapes. In addition,the entire terrain is formed by a combination of previously preparedterrain parts, and therefore, a plurality of terrain parts having thesame shape are disposed in the virtual space, so that the entire terrainis monotonous.

Meanwhile, in the case where the first deformation process is performedon each terrain part, the outer shape of the cliff object 31 has agenerally wavy shape and therefore a more natural shape as shown in FIG.8. This is also true of the boundary between the ground 34 and the riverobject 33. In addition, the displacement amount of a vertex V of aterrain part varies depending on the position of the vertex V, andtherefore, even if the same kinds of terrain parts are disposed in thevirtual space, these terrain parts are deformed to have different forms,and therefore, the entire terrain is not monotonous.

(Updating of Terrain by User)

Here, in the game of this embodiment, the user can perform apredetermined operation to cause the user character 50 to, in thevirtual space, dig a ditch, scrape a cliff object, and add a new cliffobject to the ground and a cliff object. For example, when the usercharacter 50 performs an action to scrape a cliff object, a terrainpart(s) is removed from the position where that action has beenperformed. When the user character 50 performs an action to heap earthon the ground, a terrain part(s) is newly added at the position wherethat action has been performed. The user's actions to remove, add, andreplace a terrain part(s) disposed in the virtual space will now bedescribed.

Firstly, removal of a terrain part will be described. FIG. 9 is adiagram showing a non-limiting example image that is displayed on thedisplay 12 when the user character 50 performs an action to scrape aportion of a cliff object. FIG. 10A is a diagram showing the virtualspace as viewed from above before the user character 50 performs anaction to scrape a portion of the cliff object. FIG. 10B is a diagramshowing the virtual space as viewed from above after the user character50 performs an action to scrape a portion of the cliff object.

For example, when the user character 50 is located right adjacent to thecliff object 31 as shown in FIG. 8, then if the user performs apredetermined operation, a portion of the cliff object 31 is scraped asshown in FIG. 9. Although in FIG. 9 a scraped portion of the cliffobject 31 is indicated by a dashed line, the dashed-line portion isactually not displayed on the screen after that portion of the cliffobject 31 is scraped.

Specifically, as shown in FIG. 10A, the cliff object 31 is formed ofseven terrain parts before having been scraped. When the user character50 is located near a position Pa, then if the user performs apredetermined operation, a terrain part GP1 at the position Pa isremoved as shown in FIG. 10B.

More specifically, in the situation shown in FIG. 10A, informationindicating that a terrain part GP1 is disposed at the position Pa isstored in the terrain part arrangement data. In this situation, when theuser character 50 performs an action to scrape a cliff object, theinformation indicating that a terrain part GP1 is disposed at theposition Pa is removed from the terrain part arrangement data. As aresult, the terrain part GP1 that is a portion of the cliff object 31 isremoved. Likewise, for a terrain part GP1 at a position Pb, informationindicating that a terrain part GP1 is disposed at the position Pb isstored in the terrain part arrangement data before the user character 50scrapes a cliff object. In this situation, when the user character 50performs an action to scrape a cliff object, the information indicatingthat a terrain part GP1 is disposed at the position Pb is removed fromthe terrain part arrangement data.

Next, addition of a terrain part will be described. FIG. 11 is a diagramshowing a non-limiting example image that is displayed on the display 12when the user character 50 performs an action to dig the ground and heapearth on the ground. FIG. 12A is a diagram showing a non-limitingexample virtual space as viewed from above before a terrain part GP1 isadded. FIG. 12B is a diagram showing a non-limiting example virtualspace as viewed from above after a terrain part GP1 is added.

As shown in FIG. 11, when the user character 50 is present on theground, then if the user performs a predetermined operation, a portionof the ground is scraped, so that a ditch is formed at that portion ofthe ground. When the user further performs another predeterminedoperation, a new cliff object (a terrain part GP1) is added adjacent tothe ditch. Specifically, when the user character 50 performs an actionto dig a ditch at a position Pc indicated by a dashed line of FIG. 12A,the terrain part GP1 located at the position Pc is removed, so that aditch is formed (FIG. 12B). Thereafter, when the user character 50performs an action to heap earth, a terrain part GP1 is added at aposition Pd adjacent to the ditch.

More specifically, information indicating that a terrain part GP1 isdisposed at the position Pc is removed from the terrain part arrangementdata, and information indicating that a terrain part GP1 is disposed atthe position Pd is added to the terrain part arrangement data.Thereafter, when an image is rendered, the above first deformationprocess is performed. As a result, each vertex of the new terrain partGP1 is displaced, depending on the position in the virtual space of thevertex of the new terrain part GP1, so that the new terrain part GP1 isdeformed. The displacement amounts of each vertex are calculated usingexpressions 1 and 2.

As described above, there are terrain parts that are allowed to adjoineach other and terrain parts that are not allowed to adjoin each other.When a terrain part is newly added, control is performed in such amanner that terrain parts that are allowed to adjoin each other adjoineach other (i.e., terrain parts that are not allowed to adjoin eachother do not adjoin each other). Therefore, the kind of a terrain partthat is to be added at a position is determined based on the kind of aterrain part located at a position adjacent to that position. Inaddition, when a terrain part is newly added in the virtual space, thenew terrain part is located with the vertices in an adjoining portion ofthe two adjoining terrain parts sharing the same positions.

For example, when a terrain part is added to a position Pe rightadjacent to the position Pa of FIG. 12A according to the user'soperation, a terrain part GP1 is determined as a terrain part that canadjoin the terrain part GP1 located at the position Pa. In this case, asshown in FIG. 12B, vertices of the terrain part GP1 at the position Paand vertices of the new terrain part GP1 added at the position Pe sharethe same positions in an adjoining portion between the terrain part GP1at the position Pa and the new terrain part GP1 added at the positionPe. Thereafter, the above first deformation process is performed on theterrain parts including the newly added terrain part GP1.

Thus, even when a terrain part is newly added, the vertices in anadjoining portion of adjoining terrain parts share the same positions.Therefore, when the first deformation process is performed based on thepositions of vertices in the virtual space, misalignment betweenadjoining terrain parts can be prevented.

Although not shown, the user may be allowed to replace a terrain partdisposed in the virtual space with another terrain part. Specifically,the user may be allowed to remove a terrain part disposed in the virtualspace, and newly dispose another terrain part. For example, when a firstterrain part is present at a first position, the first terrain partplaced at the first position may be replaced with a second terrain partaccording to the user's operation. In this case, before the terrain partreplacement, information indicating that the first terrain part isdisposed at the first position is stored in the terrain part arrangementdata. Thereafter, according to the user's operation, informationindicating that the second terrain part is disposed at the firstposition is stored into the terrain part arrangement data. Also in thiscase, control is performed in such a manner that terrain parts that arenot allowed to adjoin each other do not adjoin each other. In addition,control is performed in such a manner that vertices in an adjoiningportion share the same positions. Thereafter, when an image is rendered,the above first deformation process is performed.

As described above, in the first deformation process of this embodiment,each vertex of a terrain part disposed based on the terrain partarrangement data is displaced in the horizontal and depth directions,depending on the position in the virtual space thereof. The displacementamount of each vertex is calculated using a function indicating apredetermined waveform. As a result, a terrain formed by disposing aplurality of previously prepared terrain parts can be modified to lookmore natural. In addition, a terrain is formed by disposing a pluralityof terrain parts, and therefore, development efficiency can be improvedcompared to the case where an entire terrain is formed as anon-segmented object.

In addition, when a terrain part is newly disposed, the firstdeformation process is performed. Therefore, the new terrain part doesnot have a fixed shape, and therefore, the formation of a monotonousterrain can be prevented. In addition, a terrain is formed based on thepart shape data and the terrain part arrangement data. Therefore, it iseasy to update an existing terrain, i.e. a terrain part can be easilynewly disposed in an existing terrain, a terrain part can be easilyremoved from an existing terrain, a terrain part disposed in the virtualspace can be easily replaced with another terrain part, etc. Even whenupdating such as addition, removal, and replacement is performed, anatural terrain can be obtained.

In addition, the vertices of terrain parts are displaced by the GPU 22using the vertex shader function to generate an image, and therefore,each vertex can be displaced at high speed, so that a terrain can bedeformed in real time.

(Second Deformation Process)

In this embodiment, a second deformation process is performed on aterrain object that has been deformed by the first deformation processas described above to further deform the entire terrain object. In thesecond deformation process, a terrain object and another object (thehouse object 40, the tree object 41, the user character 50, etc.) on theterrain object are each entirely deformed. The second deformationprocess will now be described.

FIG. 13 is a diagram showing a non-limiting example virtual space afterthe first deformation process is performed and before the seconddeformation process is performed.

As shown in FIG. 13, in the virtual space, a ground object 34 and cliffobjects 30 and 31 are disposed as terrain objects, and a house object40, a tree object 41, and a user character 50 are disposed on theterrain objects. In addition, a virtual camera VC is set in the virtualspace. For the virtual camera VC, a CxCyCz-coordinate system fixed tothe virtual camera VC is set. The Cx-axis is the lateral direction axisof the virtual camera VC. The Cy-axis is the upward direction of thevirtual camera VC. The Cz-axis is the line-of-sight direction of thevirtual camera VC. In this embodiment, the Cx-axis is set to be parallelto the x-axis of the virtual space. The virtual camera VC is alsomovable in the height direction of the virtual space. When the virtualcamera VC is moved in the height direction, the virtual camera VC isturned around the Cx-axis (pitch direction). Because the Cx-axis is setto be parallel to the x-axis of the virtual space, the direction inwhich the line-of-sight direction of the virtual camera VC extends alongthe ground 34 is parallel to the z-axis.

The second deformation process is performed on the terrain and theobjects on the terrain of FIG. 13. FIG. 14 is a diagram showing anon-limiting example virtual space after the second deformation processis performed.

As shown in FIG. 14, in the second deformation process, the entireterrain is deformed so that the ground 34 extends along a surface of acylinder (drum). Specifically, the entire train is deformed so that theground 34 (flat reference surface) that forms a part of the terrain isat least a portion of the side surface of a cylinder having a radius ofR and a central axis parallel to the x-axis of the virtual space.Because the Cx-axis of the virtual camera VC is set to be parallel tothe x-axis of the virtual space, the entire terrain is deformed so thatthe ground 34 gradually becomes lower in the line-of-sight direction ofthe virtual camera VC (the depth direction of the screen when an imageis displayed). In addition, the objects (the house object 40, the treeobject 41, the user character 50, etc.) on the terrain are deformed sothat the objects are located along the ground 34.

Specifically, in the second deformation process, each of the vertices ofterrain parts forming a terrain and each of the vertices of objectsdisposed on the terrain are subjected to coordinate conversion so thateach vertex is turned around the x-axis. The second deformation processwill now be described in greater detail with reference to FIGS. 15 and16.

FIG. 15 is a diagram showing a non-limiting example virtual space asviewed in a direction parallel to the x-axis before the seconddeformation process is performed. FIG. 16 is a diagram showing anon-limiting example virtual space as viewed in a direction parallel tothe x-axis after the second deformation process is performed.

As shown in FIG. 15, it is assumed that the y-coordinate value andz-coordinate value of a vertex V1 on the ground 34 (a vertex V1 of aterrain part that forms a part of the ground 34) are (y1, z1). It isalso assumed that the y-coordinate value and z-coordinate value of avertex V2 of the house object 40 are (y2, z2). It is also assumed that apredetermined distance in the z-axis direction is L. Note that L is afixed value.

In this embodiment, the height of the virtual camera VC is changedaccording to the user's operation. For example, it is assumed that theposition of the virtual camera VC can be set to “low,” “normal,” and“high.” When the virtual camera VC is located at the “low” position, theline-of-sight direction of the virtual camera VC is set to a firstdirection, and the angle between the z-axis and the Cz-axis is set to arelatively small value (e.g., 0-20 degrees). In this case, an image ofthe virtual space as viewed from a side is displayed on the display 12.When the virtual camera VC is located at the “normal” position, theline-of-sight direction of the virtual camera VC is set to a seconddirection pointing further downward than the first direction, and theangle between the z-axis and the Cz-axis is set to a value (e.g., 45degrees) greater than when the virtual camera VC is located at the “low”position. In this case, an image of the virtual space as vieweddiagonally above is displayed. When the virtual camera VC is located atthe “high” position, the line-of-sight direction of the virtual cameraVC is set to a third direction pointing further downward than the seconddirection, and the angle between the z-axis and the Cz-axis is set to arelatively great value (e.g., 60-70 degrees). In this case, an image ofthe virtual space as viewed from above is displayed.

In this case, the vertices V1 and V2 of FIG. 15 are displaced tovertices V1′ and V2′ shown in FIG. 16. Specifically, the y-coordinatevalue and z-coordinate value (y′, z′) of a vertex V′ after displacementare calculated based on the y-coordinate value and z-coordinate value(y, z) of a vertex V before displacement, using expressions 3-7. Notethat the x-coordinate value of each vertex remains unchanged.

rad=θ×(z/L)  (3)

temp_y=y+R  (4)

y_t=temp_y×cos(rad)  (5)

y′=y_t−R  (6)

z′=temp_y×sin(rad)  (7)

Here, θ represents the central angle of an arc that is determined basedon the height of the virtual camera VC. R represents the radius of thearc (cylinder). Because the distance L in the z-axis direction has afixed value and θ is determined based on the height of the virtualcamera VC, R is determined based on L and θ (Rθ=L).

All the vertices of the terrain parts and the objects on the terrain aresubjected to the coordinate conversion based on expressions 3-7.Specifically, each vertex is subjected to the coordinate conversionbased on expressions 3-7, which depends on the position of the vertex inthe z-axis direction. In other words, each vertex is subjected to thecoordinate conversion based on expressions 3-7, which depends on theposition of the vertex in the depth direction along the ground 34 (flatreference surface).

As shown in FIG. 16, for example, the vertex V1 on the ground 34 isdisplaced to a position on the arc having a radius of R and a centralangle of θ. By performing similar coordinate conversion on all verticeson the ground 34, the ground 34 is deformed so as to form a portion ofthe side surface of a cylinder having a radius of R. The vertex V2 ofthe house object 40 on the ground 34 is subjected to similar coordinateconversion to be displaced to a position shown in FIG. 16. By performingsimilar coordinate conversion on all vertices of the house object 40,the house object 40 is disposed on the side surface of the cylinder.

In the second deformation process, as in the first deformation process,each vertex is displaced by the GPU 22 using the vertex shader function.Specifically, the GPU 22 performs the coordinate conversion based onexpressions 3-7 according to an instruction from the CPU 21. Thereafter,the GPU 22 performs a rendering process based on the virtual camera VC,and causes the display 12 to display an image. Specifically, each timean image is displayed on the display 12 (for each frame), the verticesof terrain parts and objects on the terrain are displaced by the GPU 22using the vertex shader function, so that the entire terrain isdeformed.

Note that θ is determined by the line-of-sight direction of the virtualcamera VC (the height of the virtual camera VC). For example, when theline-of-sight direction of the virtual camera VC is set to the firstdirection, θ is set to a first value. When the line-of-sight directionof the virtual camera VC is set to the second direction, θ is set to asecond value greater than the first value. Specifically, when theline-of-sight direction of the virtual camera VC is set to the seconddirection pointing further downward than the first direction, θ is setto a greater value. In other words, when the line-of-sight direction ofthe virtual camera VC is the second direction pointing further downwardthan the first direction, the resultant deformed ground has a greatercurvature.

Meanwhile, when the line-of-sight direction of the virtual camera VC isset to the third direction pointing further downward than the seconddirection, the value of θ is set to a third value smaller than the firstand second values. In other words, when the line-of-sight direction ofthe virtual camera VC is the third direction pointing further downwardthan the second direction, the resultant deformed ground has a smallercurvature.

Note that when the virtual camera VC is located at a position (e.g., thedirection in which the virtual space is viewed from directly above)higher than the “high” position of FIG. 15, the second deformationprocess may not be performed. In other words, when the virtual camera VCis set at a position where the entire virtual space is viewed likelooking at a map, the process of deforming the terrain and objects onthe terrain into a drum shape may not be performed.

FIG. 17A is a diagram showing a non-limiting example image that isdisplayed on the display 12 when the line-of-sight direction of thevirtual camera VC is the first direction and the second deformationprocess is not performed. FIG. 17B is a diagram showing a non-limitingexample image that is displayed on the display 12 when the line-of-sightdirection of the virtual camera VC is the first direction and the seconddeformation process is performed.

As shown in FIG. 17A, when the line-of-sight direction of the virtualcamera VC is the first direction and the second deformation process isnot performed, the horizon and the tree object 41 are displayed in anupper portion of the screen. When the second deformation process isperformed with the virtual camera VC positioned in this state, the treeobject 41 disappears, as shown in FIG. 17B. In FIG. 17B, the horizon ismoved to a lower position of the screen than in FIG. 17A, so that thearea of the sky is increased. While an image of the house object 40 asviewed from above is displayed in FIG. 17A, an image of the house object40 as viewed below is displayed in FIG. 17B.

FIG. 18A is a diagram showing a non-limiting example image that isdisplayed on the display 12 when the line-of-sight direction of thevirtual camera VC is the second direction and the second deformationprocess is not performed. FIG. 18B is a diagram showing a non-limitingexample image that is displayed on the display 12 when the line-of-sightdirection of the virtual camera VC is the second direction and thesecond deformation process is performed.

As shown in FIG. 18A, when the line-of-sight direction of the virtualcamera VC is the second direction and the second deformation process isnot performed, neither the horizon nor the sky is displayed on thescreen. When the second deformation process is performed with thevirtual camera VC positioned in this state, the horizon and the skyappear as shown in FIG. 18B.

FIG. 19A is a diagram showing a non-limiting example image that isdisplayed on the display 12 when the line-of-sight direction of thevirtual camera VC is the third direction and the second deformationprocess is not performed. FIG. 19B is a diagram showing a non-limitingexample image that is displayed on the display 12 when the line-of-sightdirection of the virtual camera VC is the third direction and the seconddeformation process is performed.

As shown in FIG. 19A, when the line-of-sight direction of the virtualcamera VC is the third direction and the second deformation process isnot performed, a portion of the house object 40 and a portion of an rockobject 42 are displayed near the upper edge of the screen, for example.When the second deformation process is performed with the virtual cameraVC positioned in this state, the entire rock object 42 appears as shownin FIG. 19B.

Note that the user character 50 may move in the depth direction of thescreen according to the user's operation. In this case, the displayrange is changed, depending on the movement of the user character 50, sothat the user character 50 is displayed on the display 12.

Specifically, “rad” is calculated using the following expression 3′instead of expression 3.

rad=θ×((z+OFFSET)/L)  (3′)

Here, “OFFSET” is determined based on the movement in the depthdirection of the user character 50. As shown in expression 3′, “rad” iscalculated based on a value obtained by adding an offset value to z.Thereafter, “rad” calculated using expression 3′ is substituted intoexpressions 4 and 7, so that the coordinate values of a converted vertexV are calculated. As a result, the entire terrain can be deformed into adrum shape, and the entirety of the drum-shaped terrain can be turnedaround the central axis of the drum, and therefore, apparent movement ofthe virtual camera VC can be achieved without actually moving thevirtual camera VC in the virtual space. Specifically, by adding anoffset value to the z-coordinate value as in expression 3′, it looks asif the virtual camera VC moved in the depth direction by the amount of“OFFSET.”

FIG. 20 is a diagram showing the virtual space as viewed in a directionparallel to the x-axis before and after deformation by adding an offsetvalue to the z-coordinate value. Comparison between FIG. 16 and FIG. 20indicates that the ground 34 and the house object 40 on the ground 34have been turned around the central axis of a cylinder in FIG. 20. Byadding an offset value to the z-coordinate value of each vertex andperforming the coordinate conversion based on expressions 3′-7, theentire terrain including the terrain and the objects on the terrain canbe turned in the circumferential direction of the side surface of acylinder. As a result, when viewed from the virtual camera VC fixed inthe virtual space, it looks as if the virtual camera VC moved in thecircumferential direction of the cylinder (the depth direction of thescreen).

As described above, in the second deformation process, each of thevertices of a flat terrain and objects (a house object, a tree object, auser character, etc.) on the terrain is subjected to coordinateconversion so that the entire terrain is deformed into a curved shape(drum shape). In addition, the curvature of the drum is changed,depending on a state (orientation or position) of the virtual camera VC.Specifically, when the line-of-sight direction of the virtual camera VCis the first direction, the curvature of the drum is decreased (θ isdecreased), and when the line-of-sight direction of the virtual cameraVC is the second direction pointing further downward than the firstdirection, the curvature of the drum is increased (θ is increased).

As a result, an image that is easy to see for the user can be provided.For example, comparison between FIG. 17A and FIG. 17B indicates that inFIG. 17B, a far area in the depth direction of the ground is notincluded in the display range, and therefore, an area near the usercharacter 50 is more easily seen by the user, so that the game can bemade more enjoyable. When the line-of-sight direction of the virtualcamera VC is the first direction (lateral direction), the curvature issmall, and therefore, even when the entire terrain is deformed into adrum shape, an image that is natural to the user can be provided. Forexample, in FIG. 17B, if the curvature is extremely great, the entireterrain looks greatly curved, so that an image that is unnatural to theuser is likely to be displayed. However, in this embodiment, when theline-of-sight direction of the virtual camera VC is the first direction(lateral direction), the curvature of the drum is set to a small value,and therefore, such an unnatural feeling is less likely to occur.

In addition, in this embodiment, as shown in FIG. 19B, when theline-of-sight direction of the virtual camera VC is the third directionpointing further downward than the second direction, θ is set to asmaller value than when the line-of-sight direction of the virtualcamera VC is the first and second directions. In other words, when thevirtual space is viewed from above, the curvature of the drum isdecreased. Therefore, when the virtual space is viewed from above, thedistortion of the virtual space is reduced, and therefore, an image thatis easy to see for the user can be provided.

In addition, in this embodiment, a flat terrain and objects on theterrain are subjected to the second deformation process, in which thevertices of the flat terrain and the objects on the terrain aredisplaced in real time by the GPU 22 using the vertex shader function.As a result, it is not necessary to previously prepare a curved terrain.In the case where a curved terrain is previously created, other objects(the house object 40 and the tree object 41) disposed on the terrainneed to be created so as to fit the curved surface, and therefore, agame creator needs to spend a lot of time and effort. Specifically, whenan object is disposed on a curved terrain, it is necessary to form thebottom surface of the object that is in contact with the ground, into acurved surface shape extending along the terrain, and it is alsonecessary to form the entire object into a shape that fits the bottomsurface. In the case where different terrains having differentcurvatures are prepared, it is necessary to create objects for eachcurvature. However, in this embodiment, a flat terrain and objectsdisposed on the terrain are previously prepared, and the vertices of theflat terrain and the objects disposed on the terrain are displaced inreal time by the GPU 22 using the vertex shader function. Therefore, itis not necessary to previously prepare a curved terrain or an objectthat fits the curved terrain. Therefore, game development efficiency canbe improved.

(Details of Game Process)

Next, a non-limiting example game process that is performed in the bodyapparatus 2 will be specifically described. Firstly, data that is storedin the body apparatus 2 will be described.

FIG. 21 is a diagram showing non-limiting example data stored in thebody apparatus 2 (the DRAM 26 thereof). As shown in FIG. 21, the bodyapparatus 2 stores a game program, part shape data, terrain partarrangement data, object data, character data, and virtual camera data.In addition to these kinds of data, the body apparatus 2 stores variouskinds of data such as operation data corresponding to the user'soperation, and other data used in a game.

The game program is for executing a game of this embodiment. The gameprogram is, for example, stored in an external storage medium, andloaded from the external storage medium to the DRAM 26 during the startof the game.

The part shape data indicates the shapes of terrain parts, such as thoseshown in FIGS. 4A-4C. Data indicating each terrain part contains aplurality of pieces of vertex data. For example, data indicating aterrain part contains, as data indicating each vertex, data indicating aposition relative to a representative vertex. When a terrain part isdisposed in the virtual space, the coordinate values in the virtualspace of each vertex included in the terrain part are determined basedon the data indicating the relative position. The part shape data is,for example, stored in an external storage medium, and loaded from theexternal storage medium to the DRAM 26 during the start of the game.

The terrain part arrangement data indicates positions of a plurality ofterrain parts, indicating what terrain part is located at what positionin the virtual space. When a plurality of terrain parts are disposed inthe virtual space based on the terrain part arrangement data, thevertices in an adjoining portion of adjoining terrain parts share thesame coordinate points. There are terrain parts that are allowed toadjoin each other and terrain parts that are not allowed to adjoin eachother. The terrain part arrangement data is previously created by a gamecreator so that two terrain parts that are not allowed to adjoin eachother do not adjoin each other. The terrain part arrangement data is,for example, stored in an external storage medium, and loaded from theexternal storage medium to the DRAM 26 during the start of the game.Note that during execution of a game process, the position of eachterrain part determined by the terrain part arrangement data is changed.For example, when updating such as addition, removal, and replacement ofa terrain part is performed according to the user's operation, theterrain part arrangement data initially stored in the DRAM 26 is updatedaccording to the updating. In this case, the terrain part arrangementdata is updated so that terrain parts that are not allowed to adjoineach other do not adjoin each other.

The object data indicates other kinds of objects (the house object 40and the tree object 41) disposed on a terrain. Each piece of object datacontains a plurality of vertices. A piece of object data contains, asdata indicating each vertex, data indicating a position relative to arepresentative vertex. When an object (e.g., the house object 40) isdisposed in the virtual space, the coordinate value in the virtual spaceof each vertex of the object is determined based on data indicating therelative position thereof. The object data is, for example, stored in anexternal storage medium, and loaded from the external storage medium tothe DRAM 26 during the start of the game.

The character data contains data indicating the user character 50disposed on a terrain. The data indicating the user character 50contains a plurality of vertices, and as data indicating each vertex,data indicating a position relative to a representative vertex. Notethat the character data may contain data indicating a character that iscontrolled by the CPU 21 (so-called CPU character).

The virtual camera data, which is related to a state of the virtualcamera VC, indicates the position in the virtual space, line-of-sightdirection, etc., of the virtual camera VC.

Next, a game process performed in the body apparatus 2 will be describedin detail. FIG. 22 is a flowchart showing a non-limiting example gameprocess performed in the processor 20 of the body apparatus 2. Theprocess of FIG. 22 is performed by the CPU 21 or the GPU 22 of the bodyapparatus 2 executing a game program. Note that FIG. 22 shows onlyprocesses related to the first and second deformation processes, anddoes not show the other processes (e.g., the process of moving the usercharacter 50 based on operation data, the process of causing the usercharacter 50 to perform a predetermined action, etc.).

As shown in FIG. 22, the CPU 21 performs an initial process (step S100).In the initial process, a fixed xyz-coordinate system is set in thevirtual space, and each terrain part is disposed in the virtual spacebased on the terrain part arrangement data. As a result, a terrainincluding a cliff object, a ground object, a river object, etc., isformed. By disposing each terrain part based on the terrain partarrangement data, the positions in the virtual space of the vertices ofeach terrain part are determined. Also in the initial process, otherobjects (the house object 40, the tree object 41, etc.) are disposed onthe terrain. When the position in the virtual space of each object isdetermined, the positions in the virtual space of the vertices of eachobject are determined. In addition, the user character 50 is alsodisposed in the virtual space. When the position in the virtual space ofthe user character 50 is determined, the positions in the virtual spaceof the vertices of the user character 50 are determined. In addition,the virtual camera VC is disposed in the virtual space.

After step S100, the CPU 21 executes step S101. Thereafter, the CPU 21executes steps S101-S110 repeatedly, i.e. at predetermined frame timeintervals (e.g., 1/60 sec).

In step S101, the CPU 21 determines whether or not to update theterrain. Specifically, the CPU 21 determines whether or not the user hasperformed the operation of adding a terrain part (e.g., the operation ofheaping earth), the operation of removing a terrain part (e.g., theoperation of scraping a cliff object, and the operation of digging theground), or the operation of replacing a terrain part.

If it is determined that the terrain is to be updated (step S101: YES),the CPU 21 updates the terrain part arrangement data stored in the DRAM26 (step S102). For example, when the user performs the operation ofadding a terrain part at a position, the CPU 21 adds, to the terrainpart arrangement data, information indicating that the terrain part isdisposed at the position. When the user performs the operation ofremoving a terrain part at a position, the CPU 21 removes the terrainpart at the position from the terrain part arrangement data. When theuser performs the operation of replacing a terrain part at a positionwith another terrain part, the CPU 21 updates the terrain partarrangement data so as to replace the terrain part at the position withthe second terrain part.

Here, the CPU 21 performs control in such a manner that when a terrainpart is newly added or a terrain part is replaced, terrain parts thatare not allowed to adjoin each other do not adjoin each other. Forexample, when a terrain part is added at a position, the CPU 21determines the kind of the newly added terrain part based on the kind ofa terrain part located at a position adjacent to the position of thenewly added terrain part. Thereafter, the CPU 21 places the new terrainpart in such a manner that the vertices in an adjoining portion ofadjoining terrain parts share the same positions.

If step S102 has been executed or if the determination result of stepS101 is negative (NO), the CPU 21 performs a virtual camera settingprocess (step S103). Specifically, the CPU 21 sets the height(line-of-sight direction) of the virtual camera VC according to theuser's operation. When the user changes the height of the virtual cameraVC, the CPU 21 sets the height (position and line-of-sight direction) ofthe virtual camera VC. When the user performs the operation of movingthe user character 50 in the lateral direction (x-axis direction), instep S103 the CPU 21 moves the virtual camera VC in the lateraldirection (x-axis direction) of the virtual space according to theoperation.

Following step S103, the CPU 21 sets the central angle θ, depending onthe state of the virtual camera VC (step S104). Specifically, the CPU 21sets the central angle θ based on the line-of-sight direction (height)of the virtual camera VC set in step S103.

Next, the CPU 21 determines whether or not the user character 50 hasmoved in the depth direction (z-axis direction) according to the user'soperation (step S105).

If it is determined that the user character 50 has moved in the depthdirection (step S105: YES), the CPU 21 sets an offset value (step S106).The offset value set in this case is the “OFFSET” of expression 3′.Specifically, the CPU 21 sets the offset value based on the movement ofthe user character 50 in the z-axis direction. For example, the CPU 21sets a negative offset value if the user character 50 has moved in thepositive z-axis direction, and a positive offset value if the usercharacter 50 has moved in the negative z-axis direction.

If step S106 has been executed or if the determination result of stepS105 is negative (NO), the CPU 21 causes the GPU 22 to execute the firstdeformation process for deforming the vertices of each terrain part(step S107). Specifically, the GPU 22 displaces the vertices of eachterrain part disposed in the virtual space based on the terrain partarrangement data, using the vertex shader function, based on expressions1 and 2. As a result, the vertices of each terrain part are displacedaccording to the position in the virtual space, so that the terrain isdeformed as shown in FIG. 6.

Following step S107, the CPU 21 causes the GPU 22 to execute the seconddeformation process of deforming the terrain and the objects on theterrain (step S108). The GPU 22 displaces the vertices of the terraindeformed by the first deformation process and the objects on theterrain, using the vertex shader function, so that the resultantvertices form a drum shape. Specifically, the GPU 22 displaces thevertices of each terrain part deformed by the first deformation processand the objects (the house object 40, the tree object 41, the usercharacter 50, etc.) on the terrain, using expressions 3-7. By performingthe second deformation process, the flat ground is deformed to form aportion of the side surface of a cylinder, and the objects on the groundare disposed on the side surface of the cylinder. Note that if theoffset value has been set in step S106, the displacement of the verticesis calculated using expression 3′.

Thereafter, the CPU 21 causes the GPU 22 to perform a rendering processbased on the virtual camera VC (step S109). Specifically, the GPU 22generates an image of the terrain and the objects on the terrain thathave been deformed by the first and second deformation processes, asviewed from the virtual camera VC. The generated image is output to thedisplay 12, on which the image of the virtual space is displayed (stepS110).

Note that the first deformation process of step S107 and the seconddeformation process of step S108 are performed only on vertices includedin the image capture range of the virtual camera VC. In other words, thefirst and second deformation processes are not performed on verticesthat are not included in the image capture range of the virtual cameraVC. Specifically, the first and second deformation processes areperformed on vertices that will be included in the viewing frustum ofthe virtual camera VC after the first and second deformation processeshave been performed.

If step S110 has been performed, the CPU 21 executes step S101 again.Thus, FIG. 22 has been described.

Thus, the first deformation process of step S107 and the seconddeformation process of step S108 are executed repeatedly, i.e. at frametime intervals. Even when a terrain part is added, remove, or replaced,the first and second deformation processes are performed in real time.

As described above, in this embodiment, the first deformation process isperformed on a terrain formed by disposing a plurality of terrain partsbased on the terrain part arrangement data. In the first deformationprocess, the vertices of terrain parts are each displaced in the x-axisand z-axis directions, depending on the position thereof in the virtualspace. The displacement amount of each vertex is determined by afunction representing a predetermined waveform. Specifically, thedisplacement amount is determined based on expressions 1 and 2. By thefirst deformation process, a terrain formed by disposing a plurality ofkinds of terrain parts can be changed to look natural. In addition, aterrain is formed by disposing a plurality of terrain parts, andtherefore, a terrain can be more efficiently created than when an entireterrain is individually created, resulting in an improvement in gamedevelopment efficiency. In addition, updating (addition, removal,replacement, etc.) of a terrain part can be easily performed, resultingin extensibility.

In, this embodiment, in addition to the first deformation process, thesecond deformation process of deforming the entire terrain into a curvedshape is performed. As a result, the entire terrain can be deformed soas to be easily seen by the user, and it is not necessary for a gamecreator to previously create a deformed terrain (curved terrain) or anobject on a deformed terrain. Therefore, the cost and time ofdevelopment can be reduced, resulting in an improvement in developmentefficiency.

(Variations)

In the foregoing, the image processing of this embodiment has beendescribed. The above embodiment is merely for illustrative purposes. Thefollowing variations may be additionally provided, for example.

For example, in the above embodiment, it is assumed that each terrainpart has a square shape in the x-axis and z-axis directions. In otherwords, each terrain part has a square shape as viewed in the y-axisdirection. A terrain is formed by disposing such terrain parts in a gridpattern. However, such a terrain part shape is merely for illustrativepurposes. Each terrain part may have a predetermined shape (e.g., asquare, rectangle, rhombus, parallelogram, triangle, or polygon) asviewed in the y-axis direction. Specifically, terrain parts may have thesame predetermined shape in the x-axis and z-axis directions, and aterrain may be formed by disposing a plurality of terrain parts havingthe same predetermined shape. The first and second deformation processesmay be performed on such a terrain.

In the above embodiment, it is assumed in the first deformation process,each terrain part is displaced in the x-axis direction (lateraldirection) and z-axis direction (depth direction) of the virtual space,and is not displaced in the y-axis direction (height direction). Inanother embodiment, each terrain part may also be displaced in theheight direction of the virtual space. In still another embodiment, inthe first deformation process, each terrain part may be displaced in atleast one of the lateral direction, depth direction, and heightdirection of the virtual space.

In the above embodiment, in the first deformation process, the verticesof a terrain part are displaced using a function having a predeterminedwaveform (expressions 1 and 2). Alternatively, the vertices of a terrainpart may be displaced using any other suitable function. In addition,the vertices of a terrain part may be displaced randomly, depending onthe positions thereof.

In the above embodiment, in the first deformation process, terrainobjects (a ground object and a cliff object) are deformed, and otherobjects on terrain objects are not deformed. In another embodiment, inthe first deformation process, other objects (the house object 40, thetree object 41, the user character 50, etc.) on terrain objects may alsobe deformed.

In the above embodiment, it is assumed that the orientation of thevirtual camera VC is changeable only around the x-axis. In other words,it is assumed that the orientation of the virtual camera VC ischangeable only in the pitch direction. In another embodiment, theorientation of the virtual camera VC may be changeable around the y-axis(yaw direction). In this case, in the second deformation process, theground may be deformed into a drum shape so that when the Cz-axis of thevirtual camera VC is projected onto a flat reference surface (theground) of the virtual space, the Cz-axis projected on the flatreference surface points in the circumferential direction of a cylinder.In other words, an entire terrain may be deformed by performingcoordinate conversion of vertices, depending on the positions of thevertices in the depth direction along the flat reference surface, sothat the flat reference surface (ground) is changed to form the sidesurface of a cylinder having a central axis pointing in a directionperpendicular to the line-of-sight direction of the virtual camera.

In the above embodiment, in the second deformation process, the groundas a flat reference surface is deformed into a drum shape. In anotherembodiment, the flat reference surface is not limited to the ground. Forexample, the flat reference surface may be the sea surface. The flatreference surface may be internally set in the virtual space and may notactually be displayed in the game. In this case, a terrain displayed asan image may be formed based on the flat reference surface. In thesecond deformation process, the reference surface is deformed into theside surface of a cylinder, so that the entire terrain is also deformedinto a drum shape.

In the above embodiment, in the second deformation process, the ground(flat reference surface) is deformed into a drum shape. In anotherembodiment, in the second deformation process, the ground may bedeformed into other curved shapes. For example, in the seconddeformation process, the ground may be deformed into a spherical shape(all or a portion of a sphere). Specifically, coordinate conversion ofeach vertex may be performed so that the ground forms all or a portionof the surface of a sphere. Alternatively, for example, each vertex maybe displaced so that the ground is deformed in a direction opposite tothat of FIG. 16 (upward in FIG. 16).

In the above embodiment, in the first and second deformation processes,each vertex is displaced by the GPU 22 using the vertex shader function.In another embodiment, each vertex may be displaced by the CPU 21.

The process of the above flowchart is merely for illustrative purposes.The order and details of the steps may be changed as appropriate.

The above game is merely for illustrative purposes. The firstdeformation process and/or the second deformation process may beperformed in any other suitable games.

In the above embodiment, it is assumed that the above process isperformed in the body apparatus 2 of the game system 1. Alternatively,the above process may be performed in any other suitable informationprocessing apparatuses (e.g., a personal computer, smartphone, andtablet terminal), etc. In still another embodiment, the above processmay be performed in an information processing system including aplurality of apparatuses (e.g., a system including a terminal and aserver).

In the foregoing, this embodiment has been described. The abovedescription is merely an illustration of this embodiment, and variousmodifications and changes may be made thereto.

While certain example systems, methods, devices and apparatuses havebeen described herein, it is to be understood that the appended claimsare not to be limited to the systems, methods, devices and apparatusesdisclosed, but on the contrary, are intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. An information processing apparatus thatexecutes: disposing a terrain object representing a terrain in a virtualspace; disposing a second object on the terrain object; setting adeformation parameter indicating a degree of deformation of the terrain;performing coordinate conversion on vertex coordinates included in theterrain object and the second object so as to deform the entire terrainto the degree corresponding to the deformation parameter; and renderingthe terrain object and the second object after the coordinate conversionis performed, based on a virtual camera.
 2. The information processingapparatus according to claim 1, wherein the information processingapparatus includes a graphics processor having a vertex shader function,and the graphics processor performs the coordinate conversion using thevertex shader function.
 3. The information processing apparatusaccording to claim 1, wherein the deformation parameter is related to acurvature, the terrain object includes a flat reference surface, and thecoordinate conversion is performed on the vertex coordinate so as tochange the flat reference surface to a curved surface shape depending onthe deformation parameter.
 4. The information processing apparatusaccording to claim 3, that further executes: controlling the virtualcamera, wherein the deformation parameter is set, depending on a stateof the virtual camera.
 5. The information processing apparatus accordingto claim 4, wherein a line-of-sight direction in the virtual space ofthe virtual camera is allowed to be set to a first direction or a seconddirection pointing further downward than the first direction, and thedeformation parameter is set so that the curvature is a first curvaturewhen the line-of-sight direction of the virtual camera is the firstdirection, and the curvature is a second curvature greater than thefirst curvature when the line-of-sight direction of the virtual camerais the second direction.
 6. The information processing apparatusaccording to claim 5, wherein the line-of-sight direction in the virtualspace of the virtual camera is allowed to be set to a third directionpointing further downward than the second direction, and the deformationparameter is set so that the curvature is a third curvature smaller thanthe first and second curvatures when the line-of-sight direction of thevirtual camera is the third direction.
 7. The information processingapparatus according to claim 4, wherein the virtual camera is allowed tobe set to view the terrain object in the virtual space from directlyabove, and when the virtual camera is set to view the terrain object inthe virtual space from directly above, the coordinate conversion is notperformed.
 8. The information processing apparatus according to claim 3,wherein the deformation parameter related to the curvature indicates anangle, and the coordinate conversion is performed on each vertexcoordinate, depending on a position of the vertex coordinate in a depthdirection along the flat reference surface, so as to convert the flatreference surface into a surface forming a portion of the side surfaceof a cylinder, where a line extending in the depth direction along theflat reference surface forms an arc having a central angle equal to theangle indicated by the deformation parameter.
 9. The informationprocessing apparatus according to claim 8, wherein the coordinateconversion is performed on each vertex coordinate after a value is addedto a coordinate value indicating a position of the vertex coordinate inthe depth direction along the flat reference surface.
 10. Anon-transitory computer-readable storage medium having stored therein aninformation processing program for causing a computer of an informationprocessing apparatus to execute: disposing a terrain object representinga terrain in a virtual space; disposing a second object on the terrainobject; setting a deformation parameter indicating a degree ofdeformation of the terrain; performing coordinate conversion on vertexcoordinates included in the terrain object and the second object so asto deform the entire terrain to the degree corresponding to thedeformation parameter; and rendering the terrain object and the secondobject after the coordinate conversion, based on a virtual camera. 11.The non-transitory computer-readable storage medium according to claim10, wherein the computer includes at least a graphics processor having avertex shader function, and the information processing program causesthe graphics processor to perform the coordinate conversion using thevertex shader function.
 12. The non-transitory computer-readable storagemedium according to claim 10, wherein the deformation parameter isrelated to a curvature, the terrain object includes a flat referencesurface, and the coordinate conversion is performed on the vertexcoordinate so as to change the flat reference surface to a curvedsurface shape depending on the deformation parameter.
 13. Thenon-transitory computer-readable storage medium according to claim 12,wherein the information processing program causes the computer tofurther execute: controlling the virtual camera, wherein the deformationparameter is set, depending on a state of the virtual camera.
 14. Thenon-transitory computer-readable storage medium according to claim 13,wherein a line-of-sight direction in the virtual space of the virtualcamera is allowed to be set to a first direction or a second directionpointing further downward than the first direction, and the deformationparameter is set so that the curvature is a first curvature when theline-of-sight direction of the virtual camera is the first direction,and a second curvature greater than the first curvature when theline-of-sight direction of the virtual camera is the second direction.15. The non-transitory computer-readable storage medium according toclaim 14, wherein the line-of-sight direction in the virtual space ofthe virtual camera is allowed to be set to a third direction pointingfurther downward than the second direction, and the deformationparameter is set so that the curvature is a third curvature smaller thanthe first and second curvatures when the line-of-sight direction of thevirtual camera is the third direction.
 16. The non-transitorycomputer-readable storage medium according to claim 13, wherein thevirtual camera is allowed to be set to view the terrain object in thevirtual space from directly above, and when the virtual camera is set toview the terrain object in the virtual space from directly above, thecoordinate conversion is not performed.
 17. The non-transitorycomputer-readable storage medium according to claim 12, wherein thedeformation parameter related to the curvature indicates an angle, andthe coordinate conversion is performed on each vertex coordinate,depending on a position of the vertex coordinate in a depth directionalong the flat reference surface, so as to convert the flat referencesurface into a surface forming a portion of the side surface of acylinder, where a line extending in the depth direction along the flatreference surface forms an arc having a central angle equal to the angleindicated by the deformation parameter.
 18. The non-transitorycomputer-readable storage medium according to claim 17, wherein thecoordinate conversion is performed on each vertex coordinate after avalue is added to a coordinate value indicating a position of the vertexcoordinate in the depth direction along the flat reference surface. 19.An information processing system that executes: disposing a terrainobject representing a terrain in a virtual space; disposing a secondobject on the terrain object; setting a deformation parameter indicatinga degree of deformation of the terrain; performing coordinate conversionon vertex coordinates included in the terrain object and the secondobject so as to deform the entire terrain to the degree corresponding tothe deformation parameter; and rendering the terrain object and thesecond object after the coordinate conversion, based on a virtualcamera.
 20. An information processing method to be executed in aninformation processing system, the information processing methodcomprising: disposing a terrain object representing a terrain in avirtual space; disposing a second object on the terrain object; settinga deformation parameter indicating a degree of deformation of theterrain; performing coordinate conversion on vertex coordinates includedin the terrain object and the second object so as to deform the entireterrain to the degree corresponding to the deformation parameter; andrendering the terrain object and the second object after the coordinateconversion, based on a virtual camera.